This is what the WGA summary says about the AI provisions:
We have established regulations for the use of artificial intelligence (“AI”) on MBA-covered projects in the following ways:
AI can’t write or rewrite literary material, and AI-generated material will not be considered source material under the MBA, meaning that AI-generated material can’t be used to undermine a writer’s credit or separated rights. A writer can choose to use AI when performing writing services, if the company consents and provided that the writer follows applicable company policies, but the company can’t require the writer to use AI software (e.g., ChatGPT) when performing writing services. The Company must disclose to the writer if any materials given to the writer have been generated by AI or incorporate AI-generated material. The WGA reserves the right to assert that exploitation of writers’ material to train AI is prohibited by MBA or other law.